1. Field of the Invention
The present invention relates to a seat cushion pumping device for a vehicle, and more particularly to an improved pumping device, which is adapted to adjust a height of a vehicle seat cushion in conformity with the body shape of a driver or passenger.
2. Description of the Related Art
As well known to those skilled in the art, a pumping device for a vehicle functions to adjust a height of a seat cushion constituting a vehicle seat in conformity with the body shape of a driver or passenger.
Various seat cushion pumping devices have been developed and used. The applicant of the present invention also had developed various kinds of pumping devices including a drum brake, and had filed one of them in the Korean Industrial Property Office as Serial No. 10-2002-013741. Now, a conventional pumping device disclosed by the applicant of the present invention will be explained as below with reference to FIG. 13.
As shown in FIG. 13, the conventional seat cushion pumping device, designated as reference numeral 100, comprises a clutch unit 110 adapted to generate an operating force required for adjusting a height of a seat cushion, and a brake unit 150 adapted to conserve the operating force of the clutch unit 110. The clutch unit 110 and the brake unit 150 are arranged at both front and rear sides of a base 115 positioned halfway between a body 113 and a cover 114. That is, the clutch unit 110 is interposed between the cover 114 and one side of the base 115, and the brake unit 150 is interposed between the body 113 and the other side of the base 115.
The clutch unit 110 comprises a pair of clutch blocks 117 configured to be accommodated in a clutch recess 116 defined on one surface of the base 115, a lever block 118 interposed between the pair of clutch blocks 117 and adapted to operate them, and a lever 120 coupled around the lever block 118 by interposing a lever spring 119 for use in the restoration thereof.
The brake unit 150 comprises a link connection gear 152 secured around a shaft 135 penetrating through a shaft hole 151 defined in the body 113 and meshed with gears of link means, conventionally known in the art and usable for adjusting the height of the seat cushion, and an operating plate 154 secured around the shaft and accommodated in a receiving recess 153 defined on one surface of the body 113.
The brake unit 150 further comprises power transmission pins 155 formed at the other surface of the base 115 and adapted to transmit the operating force of the clutch unit 110 to power transmission grooves 156 defined on an outer circumferential surface of the operating plate 154. Each of the power transmission pins 155 is provided at both sides thereof with pin pushers.
The operating plate 154 has flattened portions 157, and is defined at both ends of the respective flattened portions 157 with a pair of inclined wedge-shaped grooves 161.
As another constituent component of the brake unit 150, brake pins 160 are accommodated, respectively, in spaces defined between the respective inclined wedge-shaped grooves 161 and the body 113, and are adapted to transmit the operating force of the base 115 only in an operating direction while preventing the transmission of the operating force in a reverse direction.
As yet another constituent component of the brake unit 150, brake springs 162 are installed, respectively, between two brake pins 160, and are adapted to fixedly maintain the brake pins 160 in the space defined between the inclined wedge-shaped grooves 161 and the body 113. In this case, the pin pushers integrally formed at both sides of the respective power transmission pins 155 serve to release the brake pins 160 when the lever 120 is returned to its original position.
The conventional seat cushion pumping device 100 suffers from defects in that, in operation, the clutch unit comes into frictional contact with an inner circumferential surface of a drum included in the base by means of the clutch blocks operated by the lever block, and frictional surfaces there between are concentrated on the same line, resulting in an incomplete clutching operation.
An additional defect of the conventional seat cushion pumping device consists in that, in relation to the lever block adapted to operate the clutch blocks, its relatively short radius from a center point to an outer circumferential surface thereof tends to generate an excessive load in operation, resulting in an increase in wear of constituent components.
Yet another defect of the conventional seat cushion pumping device consists in that, in relation to the brake unit, although the operating plate and brake pins are arranged equiangularly in three directions thus exhibiting visual stability, they cannot sufficiently resist the overall region of the body during an actual braking operation, resulting in a deterioration in a braking force due to a stress concentration phenomenon, thus causing a deterioration in durability, quality, and operation capability of the pumping device itself.